Christopher ate 4 slices of pie. Umaima ate 3 slices. If Christopher ate $\dfrac{4}{9}$ of the pie, what fraction of the pie is remaining?
If 4 slices represent $\dfrac{4}{9}$ of the pie, there must have been a total of 9 slices. $\text{fraction of pie remaining} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 7 slices, which leaves 2 out of 9 slices remaining. There is $\dfrac{2}{9}$ of the pie remaining.